President Donald Trump is moving aggressively to undo policies designed to keep the carbon-cutting promises the U.S. made alongside nearly 200 other countries in Paris, while stopping short of a decision to formally withdraw from that landmark climate accord.

Trump will sign an executive order Tuesday that begins unraveling a raft of rules and directives to combat climate change, which President Barack Obama wove into the fabric of the federal government as he made addressing the issue a centerpiece of his second term.

The changes stem from Trump’s desire to advance the U.S. economy and domestic production of energy from fossil fuels as well as nuclear and renewable sources, while still protecting the air and water, a senior White House official told reporters Monday.

EPA Administrator Scott Pruitt told Fox and Friends Tuesday that Trump was "coming to the EPA to set a new course" that is "pro growth, pro jobs and pro environment."

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EPA Administrator Scott Pruitt says he wants to ease the burden environmental restrictions have had on American businesses.Photo: Getty Images

Trump, who once called climate change a hoax, has vowed to reorient the federal government so that U.S. oil and coal producers thrive, while manufacturers aren’t burdened by "job-killing" restrictions.

“A lot of people are going to be put back to work, a lot of coal miners are going back to work,” he said during a rally in Louisville, Kentucky last week.

Some changes will happen immediately, such as the repeal of a 2016 policy that encouraged federal regulators to consider climate change in environmental reviews as well as directives from Obama that compelled government agencies and the military to factor the phenomenon into their planning. The Interior Department also will swiftly rescind a moratorium on the sale of new rights to extract coal on federal land.

And the Trump administration also is tossing an Obama-era "social cost of carbon" metric that estimated the potential economic damage from climate change and was used to justify a slew of environmental actions, from efficiency standards for microwave ovens to the revamp of government buildings. Instead, the government will return to an earlier 2003 approach for estimating the potential costs of any regulations governing greenhouse gas emissions.

Other policy pivots will take years of work, such as reversing the Clean Power Plan that forced states to cut greenhouse gas emissions from electricity. An Interior Department rule setting requirements for hydraulic fracturing on federal land will be rescinded. And a pair of regulations governing potent methane emissions from oil and gas wells also will be reviewed at the Environmental Protection Agency and the Interior Department -- with possible changes or a reversal years away.

Most -- if not all -- of the changes will face legal challenges from the same environmentalists who already are fighting to defend Obama’s Clean Power Plan in federal court.

"In taking a sledgehammer to U.S. climate action, the administration will push the country backward, making it harder and more expensive to reduce emissions," Andrew Steer, president of the World Resources Institute, said in an emailed statement. "Climate science is clear and unwavering: mounting greenhouse gas emissions are warming our planet, putting people and business in harm’s way."

The news was cheered by some conservatives who have been pushing Trump to go even further in stripping climate regulations from the rulebooks, including by undoing the EPA’s landmark declaration that greenhouse gas emissions jeopardize the public health and welfare. That 2009 endangerment finding served as the underpinning for later EPA carbon rules.

Myron Ebell, director of the Competitive Enterprise Institute’s Center for Energy and Environment, cast Trump’s executive order as a good start.

"It takes the necessary first steps in undoing President Obama’s energy-rationing agenda," Ebell said by email. "Of course, there is more work to be done down the road, most importantly withdrawing from the Paris climate treaty and reopening the endangerment finding."

The Trump administration hasn’t said if the U.S. will remain a part of the 2015 Paris climate accord -- despite the president’s campaign pledges to rip up the deal that set broad, non-binding carbon-cutting targets for the U.S. and nearly 200 other countries. Whether the U.S. remains in the pact is still under discussion, according to the senior White House official.

Secretary Tillerson

Secretary of State Rex Tillerson has advocated the U.S. keep its seat at the table by sticking with the plan. Even without formally pulling out of the Paris pact, the U.S. is abandoning its pledge to pay $3 billion into a United Nations fund to help countries on the front lines of climate change.

Trump’s actions are politically significant, following months of promises to reverse the fortunes of struggling coal miners -- campaign vows that helped propel him to victory in industrial strongholds like West Virginia and Pennsylvania. Although the changes he is setting in motion will make it cheaper to extract coal and use it to generate electricity, they are unlikely to dramatically boost domestic demand for coal, which faces stiff competition from cheap natural gas and is affected by other pollution regulations untouched by Trump’s order.

And mining jobs have been in decline for decades as automated equipment increasingly unearths coal, doing the work that once required pick axes and mules.

Even before the Obama administration imposed the coal-leasing moratorium in January 2016, coal producers had little interest in adding new federal reserves to their portfolios, amid slumping domestic demand. Existing federal leases contain at least 20 years’ worth of coal, according to Interior Department estimates.

It was not immediately clear Monday whether Trump’s Interior Department would continue a broad review of the federal coal leasing program even as it restarts sales; that analysis is already about a third complete, with regulators unveiling a broad blueprint of possible changes earlier this year.

Sierra Club Executive Director Michael Brune called Trump’s order "the single biggest attack on climate action in U.S. history" and said it was a misguided attempt to help workers displaced by the global shift to cleaner energy sources.

No one can say for sure how this polar bear ended up on this lonely ice pontoon, but we all know Donald Trump did it.

"The best way to protect workers and the environment is to invest in growing the clean energy economy that is already outpacing fossil fuels and ensuring no one is left behind," Brune said in an emailed statement. "At a time when we can declare independence from dirty fuels by embracing clean energy, this action could only deepen our dependence on fuels that pollute our air, water and climate while making our kids sicker."

Legal Limbo

The EPA’s Clean Power Plan was already in legal limbo, having been put on hold by the Supreme Court in February 2016, while lower court proceedings were underway. The U.S. Court of Appeals heard arguments on the challenge last September but has not ruled on the case that the Trump administration will now seek to put on hold. Environmental groups and states that support the rule and are defending it in court have vowed to fight to keep those proceedings going.

Janet McCabe, the former head of the EPA Office of Air and Radiation that helped develop the Clean Power Plan, defended the measure as a "solid, reasonable and flexible rule based on years of research and outreach that follows" an ongoing market transition toward cleaner energy. "EPA has an obligation to address carbon pollution," she said in an emailed statement. "Congress put the Clean Air Act in place to protect Americans from air pollution, and there is no doubt greenhouse gases are air pollution; the science makes that crystal clear."

Critics of the initiative said the EPA went beyond its authority under the Clean Air Act by imposing broad statewide emissions targets, rather than specific mandates for individual power plants.

"The Clean Power plan was an unprecedented power grab by the previous administration that was built on a shaky legal foundation," said Thomas Pyle, head of the American Energy Alliance, a fossil fuel-oriented free market advocacy group. "This executive order won’t get rid of the regulation overnight, but it’s an important first step that reaffirms President Trump’s commitment to protecting American families from higher energy costs."